People who teach that baptism is not necessary for salvation and say it is a ceremony after you are saved, can't show me anywhere in scripture where this is taught. 

Of course, I know it's not in scripture. 

I do know what is in scripture and Jesus commanded baptism and all those who were saved, after Jesus' death and resurrection, were baptized. There are no exceptions. 

There was no baptism into Christ before Christ was crucified and resurrected. There were baptisms (submersions) for other reasons. John the Baptist's baptism of repentance. There were Jewish baptisms, but these were all for different reasons. 

I also know there is no teachings in scripture where anyone, after Jesus was raised, who recited a "sinners prayer" and were saved. I only know of examples of people who heard the word, repented and were baptized into Christ for forgiveness of their sins. 

Nowhere in scriptures does it teach that baptism is not necessary. 

You may say, "But wait, the thief on the cross was forgiven and he was not baptized."

First, the scriptures do not say the thief was not baptized. Second, even if he was baptized, it would have been some Jewish baptism or John the Baptist's baptism. There was no baptism into Christ at the time.

You may say, "Don't you believe a person on the way to be baptized who was hit and killed by a truck is saved!?"

I don't know, there is no teachings in scripture for this sort of exception. While I can believe God is a reasonable God and would not hold it against someone in this situation, I can't teach it as a fact. 

I can't come to the conclusion that baptism is not necessary nor teach that people are saved who are not baptized based on a scenario that I contemplate in my own mind. The Bible is inconclusive in these situation. 

You may say, "Well Ephesians 2:8 says 'For by grace you have been saved through faith; and this is not of yourselves, it is the gift of God; not a result of works, so that no one may boast." Baptism is a work, so it is not necessary. 

I think you need to understand that this is talking about your works do not buy you into heaven. God does not owe it to you for your works. It does not say works has nothing to do with it. It does not say faith has nothing to do with works. 

James 2:16 and one of you says to them, “Go in peace, be warmed and be filled,” yet you do not give them what is necessary for their body, what use is that? 17 In the same way, faith also, if it has no works, is dead, being by itself. 18 But someone may well say, “You have faith and I have works; show me your faith without the works, and I will show you my faith by my works.”

The scriptures do not teach you are saved through dead faith by God's grace. The scriptures do not teach that faith is only a thought. 

Baptism is obeying a commandment. It is an appeal to God for a good conscience. (1 Peter 3:21)

You may say, "But Romans 10:8 says that if you confess with your mouth Jesus as Lord, and believe in your heart that God raised Him from the dead, you will be saved;"

Romans 10:8 doesn't mention repentance either. Does this mean repentance is not necessary for salvation?  If you teach this, you are in direct contradiction to the scriptures as a whole. If you teach that baptism is not necessary based on this verse or other verses that do not mention baptism, you are teaching something that is a direct contradiction to the scriptures as a whole. 

Romans 10:8 and other verses that do not specifically mention repentance or baptism does not teach repentance and baptism is unnecessary. 

You may say, "Why do so many churches teach that baptism is unnecissary for salvation then?"

Baptism is difficult and messy. Can you imagine one of the great evangelists, who wants contributions from a massive crowd of the unsaved, attempting to baptize them? Let's avoid baptism and teach that it is not necessary if we are asked. 

How does one of the great evangelists baptize someone who is watching them on TV? Are they instructed to go to a local church to get baptized? They want them watching their TV show and sending them contributions, not contributing to a local church! 

Like I said before, I would think God is reasonable in exceptional situations, but I can't teach that baptism is unnecessary as a fact, because the scriptures do not teach it.